ROBERTLATHAM1 Posted April 15, 2005 Report Share Posted April 15, 2005 (edited) hello guys ! i just received the specs. on my 1968 harmony 535 head! wow! what a job it was finding anything on this head! anyways the specs state it has 7 tubes (4 dual purpose "what ever that means") 5 of the tubes are 12ax7"s and 2 of the tubes are 6L6GC's now i thought that two 6l6's made 50 watts but the specs state it is 35watts true power and over 75watts peak. is there different wattages to these 6l6 tubes? and if so can i get higher wattage tubes for the head with out damageing the unit? Edited April 15, 2005 by ROBERTLATHAM1 Quote Link to comment Share on other sites More sharing options...
lovekraft Posted April 15, 2005 Report Share Posted April 15, 2005 Welcome to the wonderful world of tube amp power ratings - a pair of 6L6s can be configured to produce between 6 watts (Class A, triode mode) and over 50 watts rms, depending on the desired linearity and frequnecy response. It sounds like you've got a 35 watt rms power section - peak power has become increasingly meaningless, especially since car audio has introduced the concept of "instantaneous power", a completely amibiguous system that allows you to rate 100 watt rms amps at over 1 kilowatt. So, to cut this rant short, no, there aren't any special high-power 6L6s, just different circuit configurations for using them. Did you ever manage to get hold of a schematic for it? Quote Link to comment Share on other sites More sharing options...
Drak Posted April 15, 2005 Report Share Posted April 15, 2005 Besides the fact that the ~audible difference~ between 35W and 50W would barely be noticable, or of any major contribution, anyway. On paper it looks like a noticable difference, but in reality it's not very much at all (in audible terms). Things like a tight or mushy bass response, point of breakup, smooth or harsh trebles, and the dB sensitivity/cone variety/magnet structure of the speaker would be more important factors to consider than an extra 15W output, it's really a non-item. Quote Link to comment Share on other sites More sharing options...
Southpa Posted April 15, 2005 Report Share Posted April 15, 2005 6L6 tube series were used virtually everywhere during that era. I had an old Teisco guitar/bass amp that used them, probably a lot like your Harmony. If they are the original tubes then there is a likely chance that they will need replacing or at the very least have the output voltage biased. Does it work? And if so, any background noise? Some of those old amps can be biased with a simple screw setting. Unfortunately, I was told my Teisco needed resistors soldered in to balance things up, noisy old bugger. Quote Link to comment Share on other sites More sharing options...
ROBERTLATHAM1 Posted April 16, 2005 Author Report Share Posted April 16, 2005 lovekraft yes i have foound a scheamatic but have not recieved it yet. the guy who has it does all the tweaks for the red stripes who use silvertone very closely related to the harmony. drak as for increasing the power for volume there is no need this amp is really loud. i was just under the impression that 2-6l6 produced 50watts no matter what. southpa it works great! no noise! but as for the valves needing replacement i dont know? if replaceing the tubes means more volume i dont know that my cabinet will handel any more lmao! im sure that replaceing them would improve the tone though so yes im planning to replace them but i have no idea of what to do other than replace with what came out with. as far as different tubes go ie 6l6 vs el34 and so on dont know the difference! thanks guys this site is really great and i need to read up on how to donate. would really like to contribute! Quote Link to comment Share on other sites More sharing options...
Southpa Posted April 16, 2005 Report Share Posted April 16, 2005 Here are a couple good resources for tubes and general tube amp maintenance. There is some good info about 6L6 tubes and what else you can use as suitable replacements. I would get the two 6L6's tested and see how their relative output voltages match up. http://www.geofex.com/tubeampfaq/taffram.htm http://www.canada.com/shopping/frame.aspx?id=243 Quote Link to comment Share on other sites More sharing options...
ROBERTLATHAM1 Posted April 17, 2005 Author Report Share Posted April 17, 2005 southpa wow really great info there! i have been reading for over an hour now and cant get away from it! my brain in on tube overload lmao! i have decided to change my power tubes to the Sovtek 5881WXT as this tube , i think will acomodat my use more readily than the sylvainia that is presently in my power section. i am getting the feeling that the best tactic for finding tone i desire is to just plain expeiriment i.e buy many different tube packages then mix and match until i find what im after! thax again robert latham p.s. i donated today really love this site! Quote Link to comment Share on other sites More sharing options...
lovekraft Posted April 18, 2005 Report Share Posted April 18, 2005 Weren't the 6L6's introduced as a substitute for the KT-66's? No, that's backwards - the KT66 is actually a British redesign of the original 6L6, with slightly better linearity and slightly higher power. The 6L6 has been in production since about 1935, and is pretty much the grandaddy of all "modern" beam tetrodes. Quote Link to comment Share on other sites More sharing options...
Paul Marossy Posted April 18, 2005 Report Share Posted April 18, 2005 I like the sound of 6L6s better, but the 5881s are a little tougher. As with most things, it's a compromise. Quote Link to comment Share on other sites More sharing options...
ROBERTLATHAM1 Posted April 18, 2005 Author Report Share Posted April 18, 2005 well i was reading on alink that southpa attached (scrooll up) for the rig i use they say that the 5881's are better suited . i dont know but as i said before tubes are a mix and match thing until you find the combo you like. peace Quote Link to comment Share on other sites More sharing options...
lovekraft Posted April 18, 2005 Report Share Posted April 18, 2005 Yeah, try as many different types as you can afford - even all 6L6s are not created equal. I'm not a fan of tetrodes in general myself, except for the 6V6, but it's all about available current and personal taste. If you decide that cheap Chinese tubes sound best in your amp (not very likely, but possible), don't let anybody tell you that you've got to use NOS Mullards! Quote Link to comment Share on other sites More sharing options...
Paul Marossy Posted April 19, 2005 Report Share Posted April 19, 2005 Yep, that's true - all 6L6s are not created equal. Quote Link to comment Share on other sites More sharing options...
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